The invention relates to a system and method for a rail vehicle, and in particular, to a system and method for saving traction energy in rail vehicles.
A device known from U.S. Pat. No. 5,239,472 is used to save traction energy in rail vehicles. This device has a microprocessor as the control unit, which uses a location measured value, which is detected by a distance measurement device, and route data, which is stored in a memory (storage), to determine the distance between the rail vehicle and the respective next stop. The microprocessor uses a measured time measured value, which indicates the respective real time, and a predetermined stored timetable to determine the traveling time remaining before the rail vehicle reaches the next stop. The microprocessor then uses the distance value and the remaining traveling time, taking into account the respective speed of travel and taking into account the coasting behavior of the rail vehicle, to calculate that timexe2x80x94referred to as the recommended drive switching-off time in the following textxe2x80x94from which the rail vehicle can reach the respective next stop without being drivenxe2x80x94that is by coasting or by being brakedxe2x80x94in accordance with the timetable. The control unit is connected to an output device in the form of an indicating device. The indicating device is driven by the control unit such that it indicates the term xe2x80x9ccoastxe2x80x9d to signal the time from when the drive for the rail vehicle can be switched off. In the known device, the route data and the predetermined timetable are transferred from a computation unit on the track side to the rail vehicle, where they are stored permanently, before the rail vehicle is brought into use. Thus, the known device is an energy-saving device which indicates the time from when the next stop can be reached in accordance with the timetable without being driven, and thus without consuming energy, using the respective kinetic energy of the rail vehicle.
The invention relates to a device for a rail vehicle having a control unit which uses a measured location measured value, which indicates the location of the rail vehicle, and predetermined, stored route data, to determine the distance of the rail vehicle from the respective intended next stop. The device uses a measured time measured value, which indicates the respective time, and a predetermined stored timetable to determine the remaining traveling time to the next stop. The device forms a recommended drive switching-off time taking account of the determined distance, the determined remaining traveling time, a speed measured value which indicates the speed of the rail vehicle and predetermined coasting data which describes the coasting behavior of the rail vehicle when the drive is switched off, from which drive switching-off time the rail vehicle will reach the intended next stop on time in accordance with the respective timetable without being driven. An output device, which is connected to the control unit, is driven thereby, and produces a switching-off signal which indicates the recommended drive switching-off time.
According to an aspect of the invention, discrepancies between the actual vehicle behavior and the recommended vehicle behavior can be detected reliably.
According to one aspect of the invention, the device has a data input at which an actual value signal, which indicates the actual drive switching-off time, can be entered into the device, with the actual drive switching-off time indicating that time at which the drive was actually switched off after production of the switching-off signal. The control unit has a memory which stores the actual drive switching-off time and the respective associated, recommended drive switching-off time, for evaluation.
One advantage of the device according to this aspect of the invention is that it possible to detect discrepancies between the actual vehicle behavior of the rail vehicle and the recommended vehicle behavior. This is because the device according to this aspect of the invention has a data input at which an actual value signal, which indicates the actual drive switching-off time, can be entered into the device. When this actual value signal is present, the control unit of the device according to this aspect of the invention can thus store the actual drive switching-off time and the calculated recommended drive switching-off time and/or data signals which indicate these times, in its memory, for subsequent evaluation.
According to another aspect of the invention, to allow discrepancies in the vehicle behavior to be determined quantitatively in the device, the control unit is designed such that it forms a time difference value by forming the difference between the actual drive switching-off time and the respectively associated recommended drive switching-off time.
In some circumstances, a situation may arise in which the rail vehicle driver does not switch off the drive to the rail vehicle without delay despite appropriate signaling by the switching-off signal from the output device, so that a considerable time difference occurs between the recommended drive switching-off time and the actual drive switching-off time, and the desirable energy saving from switching off the drive is reduced or, in some circumstances, is even largely cancelled out. In order to signal this to the rail vehicle driver, according to an aspect of the invention, the control unit has an output and is designed such that it produces a warning signal at its output when the time difference value exceeds a predetermined threshold value. According to this aspect of the invention, the rail vehicle driver is made aware of the time delay, so that he can specifically improve his driving behavior. If, on the other hand, the delay is due to a technical reason in the rail vehicle, then, if the warning signals occur once or more, the device and/or the drive controller for the rail vehicle should be technically inspected and/or serviced.
According to yet another aspect of the invention, the control unit is designed such that it forms a delay value using at least the most recently formed time difference value, and determines the most recent recommended drive switching-off time furthermore taking into account the delay value which has been formed. The switching-off signal is formed using a delay value. The delay value advantageously allows, for example, the reaction time (which is always present) of the rail vehicle driver to be taken into account, with this being the time which passes between the occurrence of the switching-off signal and the rail vehicle driver producing the actual switching-off command. Specifically, if this reaction time is taken into account, then minimum or optimum energy consumption can be achieved despite the unavoidable occurrence of this delay time.
The preferable drive switching-off time can be obtained in a particularly simple, and hence advantageous manner, using the delay value if the control unit is designed such that it first calculates an auxiliary switching-off time, taking account of the determined distance, the determined remaining traveling time, a speed measured value which indicates the speed of the rail vehicle, and predetermined coasting data, which describes the coasting behavior of the rail vehicle when the drive is switched off, from which auxiliary switching-off time the rail vehicle will reach the intended next stop on time in accordance with the respective timetable without being driven, and then forms the difference between the auxiliary switching-off time and the delay value to determine an advanced drive switching-off time, and treats the advanced drive switching-off time as the recommended drive switching-off time.
In order to achieve short traveling times for the rail vehicle overall, it is preferable to avoid the rail vehicle coming to rest just by coasting to the stop since, specifically, in some circumstances coasting at very low speeds may cost a large amount of time. For this reason, the rail vehicle is generally braked in accordance with a predetermined braking profile on reaching a minimum speed. In order to take account of this situation, according to an aspect of the invention, the control unit is designed such that it determines the recommended drive switching-off time by additionally taking into account a predetermined braking profile and a predetermined minimum speed which, if undershot, would result in the rail vehicle being braked in accordance with the predetermined braking profile when it is approaching the next stop without being driven.
The invention also discloses discrepancies between the actual vehicle behavior and the recommended vehicle behavior detected reliably.
According to another aspect of the invention, there is an evaluation device which is connected to a data output, which reads the stored actual drive switching-off time and the respective associated, recommended drive switching-off time, and forms a time difference value by forming the difference between the actual drive switching-off time and the associated recommended drive switching-off time. The evaluation device may, in this case, be an evaluation device on the track side which, for example, is connected via a wire link or a radio link to the data connection of the device according to the invention.